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Our study investigated the reinforcing effect of submicron-sized (100–500 nm) Al0.5CoCrCuFeNi high-entropy alloy particles (HEAps) on the tensile properties of Al matrix composites. The HEAps were refined to the submicron-sized level via a thermal plasma process to maximize reinforcing efficiency by increasing specific surface (i.e., interface) area. The Al/HEA composites were produced by hot rolling of mechanically milled Al/HEA composite powder. The microstructural analysis demonstrated that the HEAps were uniformly dispersed within the Al matrix by forming a sound interface without interdiffusion brittle intermetallic layers or any noticeable voids. Moreover, the addition of 2 vol% HEAps resulted in a simultaneous increase in both yield strength from 355 to 403 MPa and tensile elongation from 1.3 to 3.3%. As a result, the composite experienced a synergistic effect due to the combination of intrinsic strengthening to promote uniform plastic deformation and extrinsic strengthening to mitigate plastic instability and crack propagation.

The nano-precipitates with minimal misfit strengthen Al–Zn–Mg alloys by impeding dislocation motion. However, grain boundary precipitates (GBPs) are known to have a completely incoherent relationship with the matrix, making them less effective in strengthening the alloys. Instead, GBPs are recognized for preoccupying elements such as Zn or Mg, thereby diminishing the quantity of nano-strengthening phases. GBPs significantly influence the deformation and fracture behaviors of Al–Zn–Mg alloys by accelerating stress localization and crack formation. In this study, we investigated how the accumulation of dislocations in the GBP areas leads to stress localization and subsequent cracking, using micropillar tests and crystal plasticity finite element method (CP-FEM) analysis. The dislocation pile-up in the GBPs causes stress localization around the grain boundaries, inducing crack initiation and leading to intergranular fracture. These findings enhance our understanding of the role of GBPs in the deformation and cracking of Al–Zn–Mg alloys and may pave the way for new concepts in managing GBPs.

The development of thermally conductive lightweight materials holds paramount importance for optimizing heat dissipation in automobile components. This study investigated three distinct techniques for coating graphene onto 6061 Al plates: direct, aluminum nitride (AlN)-aided, and poly-vinyl-alcohol (PVA)-aided coatings. The direct coating approach, via dipping into a graphene suspension, resulted in nonuniform graphene distribution due to the poor wettability of Al with graphene. AlN formation on the surface of a 6061 Al plate before graphene dip coating (AlN-aided coating) considerably improved the wettability of the surface with graphene. When using the PVA-aided coating method, 6061 Al plate was treated with PVA, followed by immersion in a graphene oxide (GO) suspension, achieving uniform GO coverage. This was facilitated by strong bonding between functional groups formed on the plate through treatment with PVA and those present on the GO surface. Directly coated samples exhibited a bonding strength of ∼1 MPa, whereas the samples coated using AlN- and PVA-aided methods showed bonding strengths of ∼3 and ∼10 MPa, respectively. Furthermore, AlN- and PVA-aided coatings improved thermal conductivity by ∼5.6% and ∼8.5%. This study proposes a facile and effective graphene-derivative coating process to improve the heat dissipation of Al-based materials.

Although the Inconel 706 alloy has been developed to reduce the manufacturing cost for mass production, the effect of post-heat treatment on the deformation mechanisms of this alloy system has not been well investigated yet. In this study, the effect of heat treatment conditions on the plastic deformation behavior of the Inconel 706 alloy was analyzed. The size of the coherent γ'/γ'' co-precipitates in the sample subjected to 3-step aging (3STEP) is larger than that in the sample subjected to 2-step aging (2STEP). However, the yield strength of 3STEP is lower than that of 2STEP due to the precipitate-free zone near its η phase which reduces the volume fraction of the γ'/γ'' co-precipitates. The coarsened η phase in 3STEP also acts as a crack initiation site, inducing intergranular fracture. Meanwhile, serrated flows were observed in the tensile stress-strain curve of 2STEP tested at a high temperature condition, which resulted in ductility degradation. The present result indicates that the different heat treatment conditions for the Inconel 706 alloy affect the morphology of the precipitate in the matrix, which can be attributed to their deformation behaviors.